Metal Gear series creator Hideo Kojima has seemingly confirmed as the main man behind The Phantom Pain.
In an image posted by Kojima-san himself on Twitter, you will see that he is the Producer, Game Designer and Director on a title he is currently editing a trailer for. However, what gives his involvement on The Phantom Pain away is the title of the trailer in the top left corner. It reads: "TPP_GDC2013_720p_ESRB".
Is it possible that Ground Zeroes is actually the beginning portion of Metal Gear Solid 5: The Phantom Pain? In addition, it's worth remembering that The Phantom Pain is due a new trailer at GDC next week -- the words 'GDC2013' are also clearly visible in the image below.